System for Providing and Displaying Video Information Using A Plurality of Video Sources

ABSTRACT

In one aspect, a system for providing and displaying video information in a vehicle is provided. The system includes a display device having a video input, a first camera mountable at the rear of the vehicle, the first camera having a first video output, a second camera mountable at the passenger side of the vehicle, the second camera having a second video output, wherein the first video output and the second video output are connected in parallel to the video input of the display device, and a camera control device configured to keep no more than one camera activated at a time.

TECHNICAL FIELD

The present invention generally relates to a vehicular system fordisplaying video input from a plurality of video sources, and moreparticularly, to an automotive camera system comprising two or morecameras sharing a common display.

BACKGROUND OF THE INVENTION

It is known to provide a rearward facing camera or imaging sensor ordevice at a rear of a vehicle and with a generally rearward and downwardfield of view to capture images of the area immediately rearward of thevehicle for a rear vision system or back up aid system or the like.Examples of such rear vision devices and systems are described in U.S.Pat. Nos. 7,005,974; 6,989,736; 6,757,109; 6,717,610; 6,396,397;6,201,642; 6,353,392; 6,313,454; 5,550,677; 5,670,935; 5,796,094;5,877,897; 6,097,023; and 6,498,620, and PCT Publication No. WO2004/047421 A2, which are all hereby incorporated herein by reference intheir entireties.

For parking into parallel parking spots along a street it is also knownto provide a camera mounted on the passenger side of the vehicle, facinggenerally rearward and to the side, thereby providing the driver abetter view of the curb and other objects to the side of the vehicle.

To connect two or more video sources to the same display video switchesare often used to toggle between the alternative video sources. Anexample of an in-vehicle video architecture using video switching isillustrated in U.S. Pat. No. 7,050,089, which is incorporated hereby byreference in its entirety. Video switches may be stand alone controlunits or integrated with other control units, e.g. a display device.

While a video switch is useful to share one display between two or morecameras it adds significant cost. Therefore, it is desirable to shareone display device between two or more cameras without the need for avideo switch.

SUMMARY OF THE INVENTION

In one aspect, the invention is directed to a system for providing anddisplaying video information in a vehicle. The system includes a displaydevice having a video input, a plurality of video sources each having avideo output, wherein the video outputs from the video sources areconnected in parallel to the video input of the display device, and avideo source control device configured to keep no more than one videosource activated at a time when the display is active.

In a particular embodiment, one or more of the video sources may be acamera. For example, one of the video sources may be a rear-mountedrearview camera on the vehicle. As another example, one of the videosources may be a camera mounted at the side of the vehicle to provide aview of a curb during parking of the vehicle.

The video source control device is configured to control the activationand deactivation of the video sources. The video source control devicemay further be configured to control the activation and deactivation ofthe display device. The video source control device may communicate withthe video sources through a serial data bus that is suitable forvehicular use, to instruct the video sources to activate or deactivateas desired.

In another aspect, the invention is directed to a camera for a vehicle.The camera includes an image sensor, a microcontroller and a serial datainterface. The image sensor has an image sensor video output configuredfor transmitting a stream of video captured by the image sensor to acamera video output connector. The image sensor video output includes avideo plus electrical conduit and a video minus electrical conduit. Themicrocontroller is operatively connected to the image sensor. The serialdata interface permits the microcontroller to communicate with at leastone other electronic control module in the vehicle. A resistor having aselected impedance connected in series with a switch are provided,wherein the resistor and switch connect the video plus electricalconduit and the video minus electrical conduit. The switch is openableby the microcontroller to deactivate the image sensor video output intoa high impedance state and is closable to activate the image sensorvideo output. The microcontroller is configured to comply with aselected message received from another electronic control module in thevehicle through the serial data interface by opening the switch.

In yet another aspect, the invention is directed to a method forswitching between a plurality of video sources in a vehicle, wherein thevideo sources are connected to a display device in parallel, includingone activated video source and at least one deactivated video source,comprising:

a) deactivating the activated video source; andb) activating one deactivated video source.

In yet another aspect, the invention is directed to a method forswitching between a plurality of video sources in a vehicle, wherein thevideo sources are connected to a display device in parallel, includingone activated video source and at least one deactivated video source,comprising:

a) deactivating the display device;b) deactivating the activated video source;c) activating one deactivated video source after at least one of stepsa) and b); andd) activating the video display device.

In yet another aspect, the invention is directed to a video selectionsystem, including a plurality of video sources, each having a videooutput, a video selector switch configured to selectively provide aconnection between any selected one of the video sources and a videoinput of a display device, a video source control device operativelyconnected to the video sources and to the video selector switch, suchthat the video source control device is configured to control whichvideo source is connected to the display device, and is configured topermit no more than one video source to be active at any given time whenthe display device is active.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a camera used in one aspect of theinvention.

FIG. 2 is a more detailed illustration of the video conditioning blockof FIG. 1 when used in a single-ended configuration.

FIG. 3 is a more detailed illustration of the video conditioning blockof FIG. 1 when used in a differential video configuration

FIG. 4 is a more detailed illustration of the video conditioning blockof FIG. 1 when used in a single-ended video configuration with variableresistance

FIG. 5 is a more detailed illustration of the video conditioning blockof FIG. 1 when used in a differential video configuration with variableresistance

FIG. 6 is a block diagram showing an exemplary vehicle camera systemwith two cameras, a display device and a camera control device.

FIG. 7 is a block diagram showing an exemplary video system with fourvideo sources, a display device and a video selector device.

DETAILED DESCRIPTION OF THE INVENTION

Reference is made to FIG. 6, which shows a schematic illustration of asystem 10 for displaying video input from a plurality of video sourcesfor use in a vehicle, in accordance with an embodiment of the presentinvention. The system 10 shown in FIG. 6 includes a plurality of videosources 11 which are connected in parallel to a common display device14. The video sources 11 may each be any suitable source of videosignals such as a camera (eg. a rear-mounted rearview camera or aside-mounted rearview camera), a DVD player, a vehicular navigationsystem or a connection to an external, user-supplied, electronic device.In the embodiment shown in FIG. 6, two cameras 12, shown individually at12 a and 12 b, make up the plurality of video sources. The first camera12 a may, for example, be mounted at the rear of a vehicle, and thesecond camera 12 b may be mounted at the side of the vehicle.

The cameras 12 are wired in parallel to a common video input shown at 16of the display device 14. The cameras 12 are configured such that theirvideo output shown at 17 (and shown individually at 17 a on the firstcamera 12 a and at 17 b on the second camera 12 b) can be activated anddeactivated in response to an instruction from a video source controldevice 18, which may be referred to as a camera control device 18 in theembodiment shown in FIG. 6 wherein all the video sources 11 are cameras12. The video output 17 may be referred to as the camera video output.

The camera control device 18 communicates with the cameras 12 through aserial data bus 20. The camera control device 18 activates no more thanone camera 12 at any given time and deactivates any other cameras 12 inthe system 10. In this way, the central camera control device 18 acts asa central arbitration logic, controlling which camera 12 gets access tothe display device 14 at any given time.

The central camera control device 18 may select which camera 12 isactive based on interaction with a user. For example, a switch orreconfigurable menu may be provided in the vehicle cabin that is usableby the vehicle driver to select which camera 12 to activate. The centralcamera control device 18 may also automatically select which camera 12to activate based on data received from other control units within thevehicle, such as control units that indicate gear position, steeringangle, parking spot orientation information from a navigation system, orsituational analysis information derived from an image processingsystem, a radar sensor system, an ultrasonic ranging system or a LIDARsensor system.

Optionally, the display device 14 may be configured to prevent theappearance of undesirable artifacts when switching between two cameras12. The switching the video to be displayed from one camera 12 toanother camera 12 (eg. from the first camera 12 a to the second camera12 b) may be carried out using the following method: The camera controldevice 18 temporarily deactivates the display device 14. For example,the camera control device 18 may command the display device 14 to show ablank screen. While the display device 14 is deactivated any video dataor video artifacts at its input are ignored and not visible to the userof the vehicle. Next, the camera control device 18 sends a first serialdata message along serial data bus 20 to the first, presently active,camera 12 a, instructing the first camera to deactivate its output.Responsive to the first serial data message the first camera deactivatesits output 17 a. The camera control device 18 also sends a second serialdata message along the serial data bus 20 to the second, presentlydeactivated camera 12 b. Responsive to the second serial data messagethe second camera 12 b starts producing video. Lastly, the cameracontrol device reactivates the display device 14 to show the videoreceived at its video input 16.

The above-described method need not be executed in the precise order ofsteps described. For example, the camera control device 18 may send theinstruction to deactivate to the first camera 12 a before it deactivatesthe display device 14.

It will also be noted that, in embodiments wherein the display device 14is deactivated as a first step, the activated camera need not bedeactivated prior to the activation of a deactivated camera. This isbecause crosstalk between two activated cameras 12 is permissible whenthe display device 14 is deactivated. As a result, in embodimentswherein the display device 14 is deactivated as a first step, the cameracontrol device 18 need not keep only one camera 12 active at any giventime. Instead the camera control device 18 keeps only one camera 12active at any given time when the display device 14 is activated.

The above-described method prevents the appearance of undesirableartifacts when switching between two cameras 12. It will be understoodthat the deactivation and subsequent activation of the display device 14is optional and that it is possible to practice a method of switchingbetween cameras 12 that are connected in parallel to a display device ina vehicle by: deactivating an active camera; and activating adeactivated camera, so that only one camera is activated at any giventime.

Referring to FIG. 1, the cameras 12 used within the system 10 may eachcomprise a lens 23, an image sensor 24 for receiving images from thelens 23, such as a CMOS image sensor, a video conditioning element 26,an oscillator 28, a power supply 30, a microcontroller 32, a connector34 for connecting to an electrical power source within the vehicle, aground connector 35 for connecting to ground, a serial data interface 36including a transceiver 36 a and an associated connector 36 b forcommunicating via serial data bus with another component, such as thecamera control device 18 (FIG. 6), and the video output 17. In theembodiment shown in FIG. 1, the serial data interface 36 is a CANinterface, however the serial data interface may be any other suitabletype of interface known in the art for communicating on any othersuitable bus known in the art, such as for example, LIN, Flexray, MOST,or Ethernet.

When the camera control device 18 (FIG. 6) deactivates or activates thecamera, it may do so by sending instructions to the microcontroller 32through the serial data interface 36. The microcontroller 32 thencontrols the internal components of the camera 12 as needed to carry outthe deactivation or activation.

The camera 12 communicates with the display device 14 through the videooutput 17. The video output 17 provides a composite video signal, whichmay be provided according to any suitable format, such as an NTSCstandard format.

The image sensor 24 has an image sensor video output shown at 40 whichis made up of a video plus electrical conduit 41 (which may be referredto as a video plus line) and a video minus electrical conduit 42 (whichmay be referred to as a video minus line). The image sensor video output40 passes through the video conditioning element 26 to the camera videooutput 17.

In an embodiment shown in FIG. 2, the video conditioning element 26comprises a 150 Ohm resistor 43 between the video plus line 41 and thevideo minus line 42, and a ground connection shown at 44 connected tothe video minus line 42. When two cameras 12 thus equipped are arrangedin parallel, as shown in FIG. 2 the cameras 12 have a parallelresistance of 75 Ohms, thereby complying with the standard impedanceused in 1 Vpp NTSC composite video outputs in automotive applications.

In another configuration shown in FIG. 3, the video conditioning element26 may comprise a differential video output, wherein each output line 41and 42 is connected through an individual 75 Ohm resistor 46 to ground,so that the resistance between the two output lines 41 and 42 is 150Ohm. Thus, the parallel resistance of two cameras 12 a and 12 b in theconfiguration shown in FIG. 3 is 75 Ohm.

Depending on the wiring harness configuration in a particular vehicle itmay be desirable to use an asymmetrical resistance distribution betweentwo or more cameras 12 to minimize noise coupled into the video feedfrom the cameras 12 to the display device 14. The resistance of eachparallel camera 12 may be selected as desired, while providing aparallel resistance for all cameras 12 of around 75 Ohms. In otherwords, the resistance in the cameras 12 need not be the same. Eachcamera 12 may have an individually selected resistance that may or maynot be the same as the resistance in any other camera 12 in the system10, while keeping the overall parallel resistance at or about 75 Ohms.

In another configuration, shown in FIG. 4, a switch 48 may be providedin series with a 75 Ohm resistor 50 between the output lines 41 and 42.When the camera control device 18 (FIG. 6) instructs a camera 12 todeactivate itself, one of the steps carried out by the microcontroller32 is to open the switch 48, thereby switching the image sensor videooutput 40 into a state of very high impedance (eg. several kilo-Ohms).When the camera control device 18 instructs a camera to activate itself,one of the steps carried out by the microcontroller 32 is to close theswitch 48 so that the image sensor video output 40 has a selectedoperating impedance, such as, for example 75 Ohms. The cameras 12 inparallel include one camera 12 (eg. camera 12 a) that is active and thattherefore has an output impedance of 75 Ohms, and a camera 12 (eg. thecamera 12 b) which has an impedance of several kilo-Ohms, so that theparallel resistance of the cameras 12 to be around the 75 Ohms standard.

More specifically the camera control device 18 causes the switch 48 onone camera 12 (eg. camera 12 a), thereby activating that camera, andopens the switch 48 on the other camera 12 (eg. camera 12 b) therebydeactivating the other camera. The active camera 12 a therefore has anoutput impedance of 75 Ohms, while the other camera 12 b has a very highoutput impedance of several kilo-Ohms, so that the parallel resistanceof the cameras 12 to be around the 75 Ohms standard. When it is desiredto display video from the second camera 12 b on the display device 14,the camera control device 18 opens the switch 48 on the first camera 12a and closes the switch on the second camera 12 b.

The configuration shown in FIG. 5 may be similar to the configurationshown in FIG. 4, except that the configuration shown in FIG. 5 providesa differential output, whereas the output in the configuration in FIG. 4is single-ended. Thus, the configuration shown in FIG. 5 does notinclude a ground connection to the video minus line 42.

In the embodiments shown in FIGS. 2-6, two video sources 11 (ie. twocameras 12) are shown as part of the system 10. It will be noted,however, that any suitable number of video sources 11 may be included inthe system 10. The specific resistance used in each camera, particularlyin the embodiments shown in FIGS. 2 and 3 may be selected based on theoverall number of video sources 11 connected in parallel so that aselected parallel resistance (eg. 75 Ohms) is provided.

The display device 14 may be any suitable type of display device, suchas a dashboard-mounted liquid-crystal display positioned to be viewed bythe vehicle driver. Optionally a touch-screen interface or any otheruser interface may be included on the display device 14.

Reference is made to FIG. 7, which shows a system 100 for providing anddisplaying video information in a vehicle, in accordance with anotherembodiment of the present invention. In the system 100 a plurality ofvideo sources 11 (shown individually at 11 a, 11 b, 11 c and 11 d) arecontrolled by a video source control device 18 and are connected attheir outputs 17 a, 17 b, 17 c and 17 d to four inputs 101 (shownindividually at 101 a, 101 b, 101 c and 101 d) of a video selectorswitch 102 which is itself connected at its output 106 to the input 16of the video display device 14. The video source control device 18controls the operation of the video sources 11 through the serial datanetwork 20 and also controls the operation of the video selector switch54. As in the embodiments shown in FIGS. 2-6, the video source controldevice 18 activates one video source 11 at a time while keeping allother video sources 11 deactivated.

In an exemplary embodiment, a method used to change the active videosource from video source 11 a to video source 11 c includes thefollowing steps: The camera control device 18 temporarily deactivatesthe display device 14. The video source control device 18 deactivatesthe activated video source 11 a. The video source control device 18 thenmoves the video selector switch to connect the video source 11 c to thedisplay device 14. The video source control device 18 then activates thevideo source 11 c. The camera control device 18 reactivates the displaydevice 14 to show the video received from the video source 11 c.

It will be noted that the video source control device 18 may reactivatethe display device 14 prior to activating the video source 11 c.Additionally, the control device 18 may deactivate the activated videosource 11 a prior to deactivating the display device 14.

Because only one video source 11 is producing video at any given timethe video selector switch 102 may be a simple electromechanical relay orother relatively inexpensive switching device, without requiring anyprecaution for preventing crosstalk between its inputs.

With respect to any of the above described embodiments, there may besome small time overlap during the deactivation of an active videosource and the activation of a deactivated video source. Such a timeoverlap may last for several milliseconds. In such embodiments, however,the video source control device 18 is nonetheless considered to keeponly one video source active at a given time and to hold all other videosources deactivated.

While the present invention has been described with reference toexemplary embodiments, it will be readily apparent to those skilled inthe art that the invention is not limited to the disclosed orillustrated embodiments but, on the contrary, is intended to covernumerous other modifications, substitutions, variations and broadequivalent arrangements that are included within the spirit and scope ofthe following claims.

1. A system for providing and displaying video information in a vehicle,comprising: a display device having a video input; a first cameramountable at the rear of the vehicle, the first camera having a firstvideo output; a second camera mountable at the passenger side of thevehicle, the second camera having a second video output, wherein thefirst video output and the second video output are connected in parallelto the video input of the display device; and a camera control deviceconfigured to keep no more than one camera activated at a time when thedisplay device is active.
 2. A system as claimed in claim 1, whereineach camera has an output impedance of about 150 Ohms, and the parallelresistance of the first and second cameras is about 75 Ohms.
 3. A systemas claimed in claim 2, wherein each video source has a video plus outputline and video minus output line connected together through a 150 Ohmresistor, and wherein the video minus output line is connected toground.
 4. A system as claimed in claim 2, wherein each camera has avideo plus output line and video minus output line, and wherein each ofthe video plus and video minus output lines is connected to groundthrough a 75 Ohm resistor.
 5. A system as claimed in claim 1, whereineach camera has a video plus output line and video minus output line,and a 75 Ohm resistor and a switch in series with the 75 Ohm resistorconnected between the video plus and video minus output lines.
 6. Asystem as claimed in claim 5, wherein the video minus output line isconnected to ground.
 7. A system as claimed in claim 1, wherein thefirst and the second video sources together have a parallel resistanceof about 75 Ohm.
 8. A system as claimed in claim 1, wherein the cameracontrol device is configured to send instructions to the plurality ofcameras over a serial data bus to keep no more than one camera activatedat a time when the display device is active.
 9. A system as claimed inclaim 1, wherein the video source control device is further configuredto control the activation and deactivation of the display device.
 10. Asystem as claimed in claim 1, wherein the camera control device isfurther configured to keep no more than one camera activated at a timewhen the display device is deactivated.
 11. A camera for a vehicle,comprising: an image sensor having an image sensor video outputconfigured for transmitting a stream of video captured by the imagesensor to a camera video output connector, wherein the image sensorvideo output includes a video plus electrical conduit and a video minuselectrical conduit; a microcontroller operatively connected to the imagesensor; a serial data interface configured to permit the microcontrollerto communicate with at least one other electronic control module in thevehicle; a resistor having a selected impedance connected in series witha switch, wherein the resistor and switch connect the video pluselectrical conduit and the video minus electrical conduit, wherein theswitch is openable to switch the image sensor video output into a highimpedance state and is closable to switch the image sensor video outputinto an operating impedance state, wherein the microcontroller isconfigured to comply with a selected message received from anotherelectronic control module in the vehicle through the serial datainterface by opening the switch.
 12. A camera as claimed in claim 11,wherein the video minus electrical conduit is further connected toground.
 13. A method for switching between a plurality of video sourcesin a vehicle, wherein the video sources are connected to a displaydevice in parallel, including one activated video source and at leastone deactivated video source, comprising: a) deactivating the displaydevice; b) deactivating the activated video source; c) activating onedeactivated video source after at least one of steps a) and b); and d)activating the video display device.
 14. A method as claimed in claim13, wherein step a) is carried out prior to step b).
 15. A method asclaimed in claim 13, wherein step b) is carried out prior to step a).16. A method as claimed in claim 13, wherein step c) is carried outafter step a).
 17. A method as claimed in claim 13, wherein step c) iscarried out after steps a) and b).
 18. A method for switching between aplurality of video sources in a vehicle, wherein the video sources areconnected to a display device in parallel, including one activated videosource and at least one deactivated video source, comprising: a)deactivating the activated video source; and b) activating onedeactivated video source.
 19. A method as claimed in claim 18, whereinstep a) is carried out prior to steps b). 20-32. (canceled)